WS-CDL, or Web Service Choreography Description Language, is a candidate recommendation from W3C. Although associated with W3C and Web Services, it is important to begin by stating that the Choreography Description Language (CDL) is not web service specific.

More recently the BPMN standard, under the guidance of the OMG, has introduced its own Choreography Model to complement the previous Process and Collaboration Models.

The purpose of a Choreography is to enable the interactions between a collection of peer to peer services to be described from a neutral (or global) perspective. This is different to other standards, such as WS-BPEL, that describe interactions from a service specific viewpoint.

In essence a Choreography description declares roles which will pass messages between each other, called interactions. The interactions are ordered based on a number of structuring mechanism which enables loops, choices and parallelism to be described. In WS-CDL and BPMN2 Choreography, variables used for messages and for conditionals are all situated at roles. There is no shared state rather there is a precise description of the state at each role and a precise description of how these roles interact in order to reach some notion of common state in which information is exchanged and processed between them.

In Choreography we use interactions and these structuring mechanisms to describe the observable behaviour, the messages exchanges and the rules for those exchanges and any supporting observable state on which they depend, of a system.